1. Field of the Invention
The present invention relates to switching devices and more particularly, to a capacitive proximity switch circuit which may be used as an actuating device for a variety of universal control applications, such as windshield wiper and door lock control.
2. Description of Related Art
Switching devices have a myriad of applications in the emerging technologies of today. One example, is the use of switching devices in the automotive industry for windshield wiper or door lock control. The switching devices may be activated by a detection device that is used to detect a predetermined condition that, when satisfied, causes the switching mechanism to operate. One example of this is found in European Patent Application No. 0 175 362 to Okushima which discloses a capacitive-type detection device for detecting water on a windshield to control windshield wiper systems employed on vehicles, vessels or aircraft.
Traditionally, a vehicle owner's options with regard to locking and unlocking or releasing or securing and opening his vehicle were restricted to a mechanical key. Using radio remote control, infrared remote control, alternating code process and smart card systems for locking and unlocking doors soon evolved but required an additional actuation element for actuating the unlocking and locking mechanisms. These additional actuating elements are therefore provided especially in order that the corresponding door lock of a corresponding motor vehicle is capable of being unlocked by an electronic activation circuit. The response of the electronic activation circuit, however, should not lead easily to the unlocking or locking of the door. This is especially desirable in the smart card system (and in other so-called transponder systems).
Using the teaching of this invention an especially user-friendly circuit of the type under discussion will be devised.